Risk Assessment of Mycotoxins in Ruminants and Ruminant Products
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Risk assessment of mycotoxins in ruminants and ruminant products Jouany J.P., Yiannikouris A., Bertin G. in Papachristou T.G. (ed.), Parissi Z.M. (ed.), Ben Salem H. (ed.), Morand-Fehr P. (ed.). Nutritional and foraging ecology of sheep and goats Zaragoza : CIHEAM / FAO / NAGREF Options Méditerranéennes : Série A. Séminaires Méditerranéens; n. 85 2009 pages 205-224 Article available on line / Article disponible en ligne à l’adresse : -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- http://om.ciheam.org/article.php?IDPDF=801009 -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- To cite this article / Pour citer cet article -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Jouany J.P., Yiannikouris A., Bertin G. Risk assessment of mycotoxins in ruminants and ruminant products. In : Papachristou T.G. (ed.), Parissi Z.M. (ed.), Ben Salem H. (ed.), Morand-Fehr P. (ed.). Nutritional and foraging ecology of sheep and goats. Zaragoza : CIHEAM / FAO / NAGREF, 2009. p. 205-224 (Options Méditerranéennes : Série A. Séminaires Méditerranéens; n. 85) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------- http://www.ciheam.org/ http://om.ciheam.org/ Risk assessment of mycotoxins in ruminants and ruminant products J.P. Jouany*, A. Yiannikouris** and G. Bertin** *INRA, UR1213 Herbivores, Research Centre of Clermont-Theix, F-63122 Saint-Genès Champanelle (France) **Alltech Inc., 3031 Catnip Hill Pike, Nicholasville, Ky 40356 (USA) Abstract. Mycotoxins are secondary metabolites produced by several fungi, more specifically those of the genera Aspergillus, Fusarium and Penicillium. They were discovered in the early 1960s, when more than 100,000 young turkeys died in the United Kingdom from an apparently new disease, which was named "turkey × disease". The toxin-producing fungus was identified as A. flavus and the toxin was given the name aflatoxin by virtue of its origin. Forages, cereals and protein sources such as peanuts and cottonseed are potential mycotoxin vectors in ruminant diets. New techniques for preserving wet forages, such as silages or wrapped bales, are unsafe when anaerobic conditions are not strictly controlled. Fresh grasses can also be contaminated with mycotoxins including fungal endophytes that produce toxins such as ergovaline, lolitrem B, peramins and swainsonine. It is generally considered that ruminants are less sensitive to mycotoxins than other animals. This may be due to the capacity of the ruminal microbial ecosystem to degrade or convert mycotoxins into less toxic compounds. However, there is some evidence that ruminants can be poisoned by mycotoxins, causing lower animal production or even death of animals. Part of mycotoxins ingested by ruminants can be recovered in milk or animal tissues, either in the parent form or as metabolites. The transfer rate, usually very low, is estimated at less than 1% for the major toxins. Thus animals are considered as "filters" of mycotoxins in the food chain. However, there is a risk for infants fed only on a milk diet of being exposed to mycotoxin levels that exceed the regulated limits. Although not currently authorised in Europe, some mycotoxin inactivators, based on sequestering or degrading properties, have been tested in vitro and in vivo. The mode of action of yeast -D- glucans against mycotoxins is presented, together with measures to limit the level of feed contamination by mycotoxins. Key words. Mycotoxin – Feedstuff – Ruminant – Transfer in milk – Toxicity – Risk mitigation. Gestion du risque mycotoxique chez le ruminant et dans les produits du ruminant Résumé. Les mycotoxines sont des métabolites secondaires produits par les champignons, plus particulièrement par ceux appartenant aux genres Aspergillus, Fusarium et Penicillium. Elles ont été découvertes vers 1960, après une intoxication ayant entraîné la mort de plus de 100 000 dindons en Angleterre. La toxine impliquée a été identifiée comme provenant d'A. flavus, d'où son nom d'aflatoxine. Les fourrages, les céréales, les sources protéiques issus d'arachide et de graine de coton en particulier, sont des vecteurs potentiels de mycotoxines. La conservation de fourrages humides sous forme d'ensilage ou de balles enrubannées constituent un risque majeur si les conditions anaérobies ne sont pas respectées. On peut également trouver certaines toxines issues d'endophytes qui colonisent les fourrages verts. Les ruminants sont considérés comme peu sensibles aux mycotoxines car ces dernières peuvent être métabolisées par les microbes du rumen. Toutefois, des cas fréquents d'intoxication chez la vache laitière sont imputés aux mycotoxines. Outre leur effet sur l'animal, les mycotoxines ou leurs métabolites peuvent se retrouver dans les produits animaux destinés à l'alimentation humaine, en particulier dans le lait. Le taux de transfert est faible, de l'ordre de 1%, ce qui amène le ruminant à être considéré comme un filtre efficace des mycotoxines présentes dans les produits végétaux. Le risque existe toutefois pour les nourrissons ou les jeunes enfants dont l'alimentation est essentiellement lactée, de dépasser les doses limites réglementaires. Certains additifs capables d'inactiver les mycotoxines ont été testés in vitro et in vivo. Le mode d'action des -D-glucanes de levure sur les mycotoxines sera présenté, ainsi que les moyens de limiter la contamination des aliments. Mots-clés. Mycotoxines – Aliments – Ruminant – Transfert dans le lait – Toxicité – Atténuation du risque. Options Méditerranéennes, A / no. 85, 2009 205 Nutritional and foraging ecology of sheep and goats I – Introduction In the 1960s more than 100,000 young turkeys on poultry farms in the United Kingdom died in a period of a few months from an unidentified disease, which was named "turkey × disease". Ducklings and other poultry animals were also affected, and high mortalities were observed. A careful survey of the inputs and environment of the affected farms indicated that the disease was associated with feeds and specifically with peanut meal imported from Brazil. A disease with symptoms typical of turkey × disease was reproduced when animals were fed the same peanut meal. Intensive investigations were then carried out on the suspected ingredient to identify the nature of the toxin, which was soon found to be of fungal origin. The toxin-producing fungus was identified as Aspergillus flavus (Nesbitt et al., 1962) and the toxin was accordingly called aflatoxin. There has since been a growing awareness of the potential hazards of toxins produced by fungi that contaminate food and feeds, and that might be life-threatening to animals and even humans. Historically, the oldest recognized type of human mycotoxicosis is ergotism. It is caused by toxins from Claviceps purpurea, and became epidemic in the Middle Ages when it was known as Saint Anthony's fire. Early symptoms were hallucinations with burning sensations on the hands and feet, and subsequent necrosis leading to loss of appendages. Although mycotoxins have always existed, studies on these toxins started only 40 years ago. Since then, numerous mycotoxins other than aflatoxins have been discovered, many of which have now been found to cause intoxications. The total number of mycotoxins that exist is not yet known, but there are probably thousands. Mycotoxins do not only account for human and animal disease; they have also a considerable economic impact on crops. The plant pathogenicity of the majority of mycotoxin-producing fungi harms crop production and crop quality. The importance of regulatory control of mycotoxins in the international grain trade and marketing of food and feeds is increasing, and concerns mainly exports from developing countries (Wilson, 2006). Mycotoxins present in animal feeds can be transferred to animal products, mainly milk, and go on to contaminate dairy produce in the food chain. The risk is significant mainly for high-milk consumers such as infants and children, but is not a concern for adults. Analytical difficulties arising from the complexity and diversity of the chemical structures of mycotoxins slowed progress until the 1980s. However, the development of chromatographic techniques coupled with tandem mass spectrometry has allowed a decisive advance in the study of mycotoxins over the last ten years. This paper describes the complex world of mycotoxins, their effect on ruminants, their transfer into animal products (mainly milk) and the possible ways in which the level of contamination in the food chain can be controlled. II – What are mycotoxins? 1. Definition The word mycotoxin combines the Greek mykos, fungus and the Latin toxicum, poison. Mycotoxins are produced by fungi through their secondary metabolism. Mycotoxin concentration can therefore be independent of the growth of the fungi, which is associated with the primary metabolism. The diversity of the compounds formed and the specificity of the fungal strain for mycotoxin production result from the secondary metabolism, which is usually activated by signals from the environment (cold, heat, dryness, fungicide, etc.). Among the numerous mycotoxins,